
Item is not a sales item
You have tried to create a sales document for an item that is not specified as a sales item (the Sales Item option is not selected in ).
You have opened the sales document, specified a customer, and from the Item No. column on the Contents tab, you have opened the List of Items window.
The option Sales Item in the Item Master Data record of the specific item was deselected.
You have chosen this item from the List of Items window.
You can create sales documents only for items that are specified as sales items.
Recommendation
If it has been a while from the time you have opened the List of Items window until you have actually chosen the item, close the List of Items window and open it again to refresh the display. If the status of an item has been changed, and it is no longer a sales item, this item does not appear in the refreshed list.